Didn’t Florida try this like a decade ago, and it would up being a huge waste of time and money? I think only something like 2% of applicants tested positive.
This is arguably a sign that the policy worked. One intent of testing is to deter people from using drugs in the first place.
The studies and numbers that get invoked in these conversations usually come with the assumption that drug testing is only successful if loads of people are testing positive and getting thrown off of the rolls.
Obviously, this is speculative unless you have some sense of what the base rate of drug use is in this population. With that said, 2% is very low. You would struggle to find a population with so little drug use if you picked Americans for testing at random.